Electric connection



Dec. 10, 1929. H, E, S ITH 1, 35019 ELECTRIC CONNECTION Filed Jan. 10,1924 2 Sheets-Sheet 1 Harold E7220 5m 11% W [zzvgnfor Dec. 10, 1929.SMITH 1,739,019

ELECTRIC CONNECTION Filed Jan. 10, 1924 2 Sheets-Sheet 2 W HarOZd 51 22052211 51 in uezizor Attorn eys.

Patented Dec. 10, 1929 UNITED STATES PATENT OFFICE ELECTRIC CONNECTIONApplication filed. January 10, 1924. Serial No. 685,327.

This invention relates to electric connections and has particularreference to the fittings carried by the ends of flexible conductorssometimes called cords and intended for attachment to lamp sockets, basereceptacles, wallbrackcts and other screw threaded outlets. The primaryobjects of the invention are the provision of a cheap, simple, andreliable device which can be insorted into and withdrawn from anordinary threaded socket by a substantially direct pull and requiring atmost not more than a fractional turn to tighten and loosen. Numerousconnectors are known which are attached and t5 detached by a directpull, but these are mostly of a specialized nature, while lamp bulbs aregenerally made with screw sockets. Domestic electric appliances such ascleaners, toasters, sad irons, curling tongs, heaters,

portable lamps, motors, fans, etc. are generally furnished with screwplugs adapted for attachment to lamp sockets and, one of the gravestinconveniences in their use is the necessary slow screwing into and outof those sockets with the accompanying twisting and kinking of thecords. Other objects of the invention are the provision of a device ofthis character which shall not be easily detached by pulling the cord,which shall have a minimum number of loose and movable parts,

and which shall be trouble proof and nonbreakable; while further objectsand advantages Will appear as the description proceeds.

Une of the chief features of my invention is the use of a soft flexiblecomposition such as soft rubber for holding the relatively movable partsof the device and thus dispensin with the need of small fastening parts.Thls soft material may comprise the entire body of the socket or onlythose parts and regions which require to yield or change their positionsand the contact members may be either molded permanently therein orfastened rnechanically thereto. Also the conductor wires or cord caneither be molded into the composition or attached mechanically,depending upon circumstances. For the composition ll prefer soft rubbercured at such time and temperature and with such small amounts ofsulphur and other ingredients as are well known 1n the arts for wringerrolls,

.cushion tires, rubber stoppers and the like,

although certain oils can be vulcanized to a very satisfactoryconsistency for this purpose.

In the drawings accompanying and form-' ing a part of this application lhave shown certain physical forms in which my ideas can be embodied,although it will be understood that these drawings are intended to bemerely illustrative of the general features of my invention rather thanexhaustive of particular designs' Fig. 1 is a longitudinal section and Fig. 2 a transverse section of a preferred form of cord terminalembodying my improvements; Fig. 8 is a side elevation of one of themetal contact parts; Fig. 4 is a longitudinal detail view showingamodified form of end contact; Fig. 5 is a longitudinal sectional view ofanother desirable form of my invention; Fig. 6 is a front elevation ofthe same. Fig. 7 shows a slight modification of the device shown in 5and 6; F ig. 8 is a longitudinal sectional view and Fig. 9 a crosssection of another modification; Fig. 10 is a separated perspective viewof the different metal parts thereof; Figs. 11 and 12 are illustrationsof still other modified forms;

and Fig. 13 is a sectional view of atypical form of lamp socket forwhich my improved terminal is designed.

In Figs. 1 to 6 inclusive 1 have shown a cord terminal having a unitarybody made Wholly of the soft material mentioned, the flexible conductorbeing permanently attached thereto and in Figs. 7 to 10 inclusive I haveshown the body only as made of this material, the flexible conductorbeing detachably secured; while Figs. 11 and 12 illustrate portion 2 area plurality of lateral contact members 55. In the present embodimentthese contact members are three in number,

- at 10 in Figs. 1 and 2 between adjacent lateral members.

The flexible cord 12 may be of any customary or convenient type, andgenerally comprises a pair of individual insulated wires or groups ofwires twisted together and surrounded by a flexible sheath. A portion ofthis sheath projects into the extension 3 and is adhesively sealedtherein. One of the individual wires or strands, as 13, is electricallyconnected to the ring 7, while the other, as 14, projects lengthwisethrough the bore 4 where it is fastened to the screw 15 carried by themember 16. This member 16 may be either of insulating or conductingmaterial. When it is of insulating material the screw 15 at its endconstitutes the terminal contact; when it is of the conducting materialthe whole device may be considered as the end contact regardless of theposition or of the existence of the screw 15. Exteriorly, the member 16is tapered as shown and the mouth of the bore is preferably tapered toreceive it. A rigid tube 17 which may be ofeither insulating orconducting material is inserted loosely in the bore 4 between the member16 and the base of the bore.

In its ordinary state the member 16 is loose in the bore as shown inFig. 1 and the diameter defined by the contacts 5 is such as to permitthem to be forced lengthwise into a standard threaded lamp socket, theflexibility I of the body permitting the necessary inward movement ofthe lateral contact members.

As soon as the member 16 reaches the bottom at the socket it is forcedinto wed ing engagement with the ends of the bore t ereby holding thelateral members against inward movement; the device can be seated morestrongly by a small angular turn if desired. It is permissible that this.wedging movement of the member 16 may be accomplished by longitudinalstretching of the extension 3, which i is one reason why the bore 4 iscontinued past the knob 1, although this depends to some extent upon thelength of the tube 17 and considerable tolerance is permissible. Theonly purpose of the tube 17 is to keep the conductor strand 14 fairlystraight and it is not imperative that the same be used, although itsometimes assists in removing the device from the socket. This removaliseffected chiefly by an outward pull on the knob 1, which may befacilitated by a slight angular turn to the left although this is notgenerally necessary owing to the softness of the composition. As soon asthe member 16 is freed the contact members 5 can readily approach eachother by the collapsing of the bore 4, this being also assisted by theflexibility of the composition. It is very diflicult to unseat thedevice by a lengthwise pull on the cord 12 since this serves rather topull the member 16 into wedging relation than to remove the body fromthe socket. The tapered extension 3 also supports the cord and preventsany abrupt bend which might break the wires or injure the insulation.

In Fig. 4 I have shown a modified form of end contact member andconnection therefor. In this embodiment the wire 14 is attached to ametal contact part 18 located at the foot of the bore 4 and havin at itsforward end a threaded socket receivlng the shank 19 of the conicalmember 16. I have in both these cmbodiments shown the end contact memberas removable for the purpose of introducing and withdrawing the coreabout which the body is molded.

In Figs. 5 and 6 a somewhat similar body is made of the same-softmaterial, formed ,with a knob 1 and a cylindrical portion 2 havingcontact members 5 separated by external grooves 10. The bore 4, however,opens from the rear, the forward end of the portion 2 being closed withan integral web 20 of the rubber or other like material having embeddedtherein a terminal contact member 16*. In this embodiment the differentcontact members 5 are all separate from each other, being connected onlyby the one strand 13 of the wire, the other strand 14 being connected tothe contact 16". I have here shown the knob 1 as provided with astiffening ring 21 for greater strength. The general effect of the web20 is of a flaring or conical nature so as to permit ready yielding ofthe lateral contact members upon insertion into the socket, and also towedge them outwardly upon longitudinal pressure of the contact 16 whenthe same reaches the bottom of the socket. Pull on the cord 12 alsotends to hold the device the more tightly, but pull on the knob 1* tendsto loosen the device. In this form the bore is also made larger forincreas ing the flexibility.

In both the devices heretofore described the flexible cord ispermanently molded into the fitting which exhibits certain advantages infactory production, but is not applicable to retail or replacement uses.In Fi 7 I have illustrated a modification of the device shown in Fig. 5to fit it for retail or replacement purposes. The lmob 1, body 2*, bore4*, contact 16 and web 20 appear as in Fig. 5. The contact members 5instead of being separate from each other are formed as arms from thecylindrical sleeve 24 which is 10- cated in the bore 4" and internallythreaded for the reception of the metal sleeve carried by the lug 26which last is of insulating material and is formed with a passageway 27for the reception of the wire and with suitable lugs 28 whereby it ma bescrewed in and out. The inner end 0 the lug is rovided with a post 29carrying the ongitu inally" ielding contact sleeve 30 (a sprm is here sown to permit this yielding) and t e contact member 16" terminates in awasher or other plate 31 adapted to be engaged by this sleeve. Suitablescrews 32-32 are provided for the wires, which are attached to the plug26 prior to its insertion in the body.

In Figs. 8 to 10 inclusive another type of device is shown comprisin acylindrical hollow body 2 of the soft yieIding material and a terminalor base late 35 of some hard and rigid substance suc as orcelain or hardrubber. The forward en of the member 2 is closed as before with aninclined web 20 formed at its outer end with a projection 36 having alon itudinal bore in which the end contact member and securing screw 16is removably inserted. The lateral contact members 5 consist of roundheaded rivets secured in the flexible parallel arms 37 of the sheetmetal rin 38 inserted in the mouth of the cavity 4". e base plate 35 isformed with an external lip 40 loosely receiving the body 2 and with acentral aperture 41 for the flexible cord '12. Rigidly secured to theinside of this plate is a metal contact member 42 of arcuate formadapted to fit snugl within the rin 38; and this member 42 re erablysubten s more than a half circ e in order to make certain contact at alltimes notwithstandin the flexibility of the ring 38 and the so tness ofthe body 2. Also carried by the member 35 is a metal bracket 43having atits inner end a threaded hole 44 for the rece tion of the screw 16whereby the parts 0 the plug are held together. A hollow sleeve 45 isreferably inserted between the end of the bracket 43 and bottom of therecess 4. The wire terminals are secured to the member 42 and bracket 43respectively.

Fig. 11 illustrates the simplest possible form in whicha device of'thischaracter can be made, namely. a plain cylindrical body 2 of softmaterial havin a terminal lateral contact 5 and a termina contact 16consisting merely of metal contacts to which are connected the terminalsof the cord 12. This body, however, must be made of exceedin l y softmaterial, such as spongy rubber an is not so long lived as the otherdevices, though it maybe made more cheaply. It is sufiicient if there beonly a single lateral contact as shown in Fig. 11, although it isconvenient to have other projections as shown at even though they bedummies, to render the device symmetrical in appearance and also tosupport it centrally in t e socket. Another sim 1e form which myinvention may take is s own at Fig. 12 wherein a hollow cylindrical body2 of soft material has a conical forward end 20 and a metal ring 51surrounding its open end and preferably molded in place. The lateralcontacts consist of brass screws 5 clamped upon one strand ,of the cord12 while the terminal contact consists of another brass screw 16 clampedupon the other strand of the cord. A knob part 52 is detachably securedby means of screws 53 in the ring 51.

In order that there may be no misunderstanding relative to what I meanby socket I have illustrated in Fig. 13 a simple illustration of atypical form for which my improvements are designed, the-same comprisinga shell 55 formed with rounded helical corrugations and located insidean insulating body 56. At its bottom the socket is closed by a base part57 carrying a central contact member 58 insulated from the shell 55. Thesocket wires are fastened to suitable screws 59, 59.

When my improved plug is made separable as shown in Figs. 7 to 10inclusive the parts 'thereof are preferably attached to the end contactrather than the side contacts in order that the lateral movement of thelatter may not be impeded. Indeed by making the device in the form of amore or less stilf central core surrounded by a soft flexible sleeve onwhich the side contacts are carried, the insertion of the corefacilitates the enterin of the side contacts by the lon itudinastretching thereof, while the with rawal of the core tends to shortenand thicken the sleeve, thereby holding it the more tightly. Similarl ifthe plu be turned cloc Wise when fu 1y inserted t 1e same bunching willoccur, but this can be stop ed at any desired limit by adjustingltheardness of the composition chan ing t e size of the central cavity, orthe wi th and depth of the external notches. Ihe lateral contacts mayvary in length and number from a single stud located at one side toseveral longitudinal serrated strigs. I refer to employ three contactsequi istant y spaced about the periphery since these serve to center theplug and insure good electrical connection. It will be apparent,however, that many and great changes may be made in design andappearance and. I do not restrictmyself except as shown in the priorart.

Having thus described my invention what I claim is:

1. An electric cord terminal for threaded sockets comprising a body ofsoft flexible insulating material such as soft rubber having a contactmember at its end adapted to engage the bottom of the socket and one ormore circumferentially spaced, longitudinally projecting contact membersof limited member carried by said projection adapted to engagethe bottomof the socket and one or more circumferentially spaced, longitudinallyprojecting contact members of limited angular extent carried by the sideof said body near its end adapted to engage the side wall of the socket,the exterior of said body being longitudinally channeled betweenadjacent contact members.

3. An electric cord terminal for threaded sockets comprising a hollowbody of soft flexible insulating material such as soft rubber having acontact member at its end adapted to engage the bottom of the socket andone or more longitudinally projecting contact members of limited angularextent in the side -wall adapted to engage the side wall of the socket,and the lateral contact members having projections adapted to be heldyieldingly in the threads of the socket to which the terminal isapplied.

{1. An electric cord terminal adapted to be inserted into and withdrawnfrom a threaded socket by a direct pull, characterized by havinglongitudinally extending radially yielding contact members molded in andcarried by a soft flexible substance such as soft rubber, said contactmembers having projections adapted to be held yieldingly by saidsubstance in the threads of the socket to which the terminal is applied.

5. An electric cord terminal adapted to be inserted into and withdrawnfrom a threaded socket by a direct pull, characterized by having acentral substantially rigid core and a sleeve of soft flexible materialas soft rubber surrounding said core, and one or more lateral contactscarried by said sleeve, said contacts having portions molded in andsubmerged by said flexible material and also havin projections adaptedto be held yieldingly y the elasticity of said sleev'e in, contact withthe threads of the socket to which the terminal is applied.

6; An electric cord terminal adapted to be inserted into and withdrawnfrom a threaded socket by a direct pull, characterized by having acentral substantially rigid core and a sleeve of soft flexible materialas soft rubber surrounding said core, the end of said core engaging saidsleeve, and one or more lateral contacts carried by said sleeve, saidcontact members having projections adapted to be held ieldingly by saidsubstance in the threa s of the socket to which the terminal is applied.

7. An electric cord terminal adapted to be inserted into and withdrawnfrom a threaded socket by a direct pull, characterized by having acentral substantially rigid core and a sleeve of soft flexible materialas soft rubber surrounding said core, the forward end of said corehaving a terminal contact and said core also engaging said sleeve, andone or more lateral contacts carried by said sleeve, said contactmembers having projections adapted to be held yieldingly by saidsubstance in the threads of the socket to which the terminal is applied.

8. An electric cord terminal comprising an elongated body of softflexible material as soft rubber, having in its exterior surface aplurality of longitudinal grooves, and ribs between said grooves,lateral contact members carried by said ribs, and an end contact membercarried by said body.

9. An electric cord terminal comprising an elongated body of insulatingmaterial having spaced longitudinal portions of soft flexible materialsuch as soft rubber, and laterally facing contact members carried bysaid flexible portions and adapted to yield transversely so as to beinsertible into or Withdrawable from a threaded socket by a direct pull.

In testimony whereof, I hereunto afiix my signature.

HAROLD ELNO SMITH.

